US 3888395 A
A machine for automatically producing a bib apron and for affixing a narrow strip thereto to form both the neck loop and tie elements for the apron. The machine includes a cutting mechanism having a skewed roller carrying a cutting blade which makes point contact with a second roller to divide a continuous web of nonwoven fibrous material into separate rectangular sheets. The material for the strip is folded longitudinally and is then advanced across each sheet by a feed mechanism including a capstan drive and a clamping mechanism for holding the strip in juxtaposition with the sheet. Thereafter, the strip is contacted by a pull member which draws the center of the strip in a downstream direction to form a "V". The forward corners of the sheet are then folded over the legs of the "V" and are adhesively secured to the body of the sheet to hold the strip in place. Upon the actuation of the clamping mechanism to sever the strip from its supply, the thus completed apron is advanced past three additional folding stations. The apron is folded longitudinally at the first of two of these stations and transversely at the third station to facilitate stacking and packaging.
Claims available in
Description (OCR text may contain errors)
United States Patent [1 1 Burt, Jr. et a1.
[ MACHINE FOR HANDLING SHEET MATERIAL  Inventors: George A. Burt, Jr.; William M. Neill, both of Santa Clara, Calif.
 Assignee: International Paper Company, New
 Filed: Aug. 16, 1973  Appl. No.: 388,813
 U.S. Cl. 223/1; 38/2; 223/37  Int. Cl A4lh 43/00  Field of Search 26/1, DlG. 1, 63, 65, 67,
Primary Examiner-Geo. V. Larkin Attorney, Agent, or Firm-Gary A. Walpert; Charles B. Smith 1 June 10, 1975  ABSTRACT A machine for automatically producing a bib apron and for affixing a narrow strip thereto to form both the neck loop and tie elements for the apron. The machine includes a cutting mechanism having a skewed roller carrying a cutting blade which makes point contact with a second roller to divide a continuous web of nonwoven fibrous material into separate rectangular sheets. The material for the strip is folded longitudinally and is then advanced across each sheet by a feed mechanism including a capstan drive and a clamping mechanism for holding the strip in juxtaposition with the sheet. Thereafter, the strip is contacted by a pull member which draws the center of the strip in a downstream direction to form a V". The forward corners of the sheet are then folded over the legs of the V" and are adhesively secured to the body of the sheet to hold the strip in place. Upon the actuation of the clamping mechanism to sever the strip from its supply, the thus completed apron is advanced past three additional folding stations. The apron is folded longitudinally at the first of two of these stations and transversely at the third station to facilitate stacking and packaging.
31 Claims, 48 Drawing Figures SHEET PATENTEDJUH 10 ms 1 :OOQOUODOODO wmx i 0.0x a W mWX Mb mm r W llvilllrl.
PATENTEDJUH 10 1975 ShEE? PATENTEDJUH 10 ms SHEET PATENTEDJUH 10 1915 SHEET PATENTEI] JUN 1 0 I975 SHEET PATENTEDJUH ms 3.888.395
SHEET 900 ZQB.
TDB 4 386 PRE. coum-an 395 TOTAL COUNT 49 MACHINE FOR HANDLING SHEET MATERIAL BACKGROUND OF THE INVENTION This invention relates to a machine for handling sheet material and more particularly to a machine for dividing a web of material into successive sheets and for affixing a narrow strip to each sheet to produce a garment.
There has been developed a bib apron and a method for making the same which is extremely economical and highly satisfactory in use. A representative apron of this type is disclosed in copending U.S. patent application Ser. No. 322,723 filed Jan. 1 1, 1973 by Richard A. Batt, now U.S. Pat. No. 3,801,985 and a particularly advantageous method for producing the apron is disclosed in copending U.S. patent application Ser. No. 322,722 also filed Jan. I l, l973 by Richard A. Batt and Charles B. Green. The aprons customarily are fabricated from a continuous web of nonwoven material which is provided with side seams along its longitudinal edges and is cut in a transverse direction to form suc' cessive sheets. A narrow nonwoven strip is positioned across each sheet and is uniquely oriented such that when two of the opposed corners of the sheet are folded over portions of the strip and are attached to the body of the sheet, the strip is firmly held in place to form both the neck loop and the tie elements for the apron.
To manufacture aprons and other garments of the foregoing type, it was heretofore often necessary to produce the garments on a piecework basis, with at least some of the cutting, folding, fastening and transporting operations being performed in a more or less manual fashion. The remaining operations for the most part necessitated the use of quite complicated machinery which was difficult and expensive to obtain and was occasionally unreliable in use. In addition, and this has been of special moment in the manufacture of the garments of the bib apron type, problems arose heretofore in the assembly and fastening of the neck loops and tie elements to the main body portions of the garments.
Still further difficulties were encountered, in attempting to design automated machinery for this purpose, because of the need for maintaining a satisfactory production rate while keeping the mechanical loading of the machine within reasonable limits. These latter difficulties were of particular concern in the design of the mechanism for severing the web of material to form the successive sheets. Also, problems were encountered heretofore in uniformly and smoothly advancing precise lengths of the narrow strip material to a predetermined location on the machine and then severing the strip at the appropriate point in the Operation cycle.
SUMMARY One general object of this invention, therefore, is to provide a new and improved machine for dividing a web of material into successive sheets and for affixing a narrow strip to each sheet to produce a garment.
More specifically, it is an object of this invention to provide such a machine for automatically manufacturing bib aprons and similar garments on a mass production basis.
Another object of this invention is to provide a machine of the character indicated which includes a novel cutting mechanism for separating a continuous web of material into individual sheets.
A further object of this invention is to provide a garment making machine which automatically advances a narrow strip to a series of intermittently moving sheets in timed relationship with the movement of the sheets.
Still another object of the invention is to provide a machine of the foregoing type which includes a unique mechanism for clamping the strip and then cutting it at the appropriate points in the operation cycle.
A still further object of this invention is to provide an apron making machine utilizing comparatively simple mechanical and electrical components which is economical to manufacture and thoroughly reliable in operation.
In one illustrative embodiment of the invention, a continuous web of flexible sheet material is received from a suitable source and is directed along a feed path. Beads of adhesive are applied along the longitudinal edges of the web, and a pair of folding devices are effective to form narrow edge folds and thereby produce side hems. As the web proceeds along its path, it moves past a cutting mechanism which divides the web into successive rectangular sheets.
Following the formation of a given sheet from the web, a narrow strip of material is led across the feed path on the downstream side of the cutting mechanism and is located in a precise position across the sheet. A pull member engages the strip intermediate its ends and is advanced in a longitudinal direction such that the strip forms a V". The sheet is maintained stationary at this point at a first folding station. The forward corners of the sheet are folded over the two legs of the *V" and are adhesively secured to the remaining portion of the sheet to complete the garment.
The thus completed garment continues its advance along the feed path to three succeeding folding stations. A plurality of longitudinal folds are produced in the garment at the first station, a single longitudinal fold is produced at the second station and a single transverse fold at the third station. The garment is thus reduced to a size which facilitates stacking and packaging.
in accordance with one feature of the invention, in certain particularly advantageous embodiments, the cutting mechanism for separating the web into individual sheets comprises a pair of cooperating rollers which are skewed relative to one another. A cutting blade on one of the rollers severs the web in the transverse direction and yet makes contact with the other roller at only a single point at any one time. With this arrangement, the web is rapidly and accurately cut into successive sheets while holding the mechanical loading of the mechanism within reasonable limits.
In accordance with another feature of the invention, in several important embodiments, the strip advancing unit includes a capstan drive in engagement with only a single side of the strip for applying driving force thereto. The capstan facilitates the advance of the strip from a suitable supply roll toward its position across the incoming sheets.
in accordance with still another feature of the invention, in some embodiments, the free end of the strip is advanced across the machine and is held stationary by a novel clamping unit. At succeeding points in the operation cycle the clamping unit releases the strip; moves back across the machine to its initial position and thenneatly and cleanly severs the strip.
The present invention. as well as further objects and features thereof. will be understood more clearly and fully from the following description of a preferred embodiment. when read with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIGS. IA and IB collectively comprise aside elevational view of a machine for manufacturing hih aprons in accordance with an illustrative embodiment of the invention. with portions of the strip unit of the machine omitted for purposes of clarity.
FIGS. 2A. and 2C collectively comprise an enlarged top plan new of the machine shown in FIG, 1.
FIGS 3 through II) are successive top plan views of the apron material as it is processed by the machine.
FIG. I1 is aside elevational view of the strip feeding mechanism of the machine.
FIG. 12 is an enlarged top plan view of the mechanism shown in FIG. II. together with a portion of the machine frame.
FIG. I3 is a fragmentary sectional view taken along the line 13-13 in FIG. 12.
FIG. 14 in an enlarged sectional view taken along the line I l-I4 in FIG. 2B and illustrating a timing chain for the sequential indexing of the machine.
FIG. l is a. side elevational view taken along the line IS-I5 in FIG. I4.
FIG. 16 is a top plan view of the web cutting mechanism for the machine.
FIG. 17 a front elevational view of the cutting mechanism shown in FIGI 16.
FIGS. I8. 19 and 2H are enlarged fragmentary sectional views taken along the lines l8---l8, 19-4) and 20 7.", respectively. in HQ. 17.
FIG. 2} is a still Iurther enlarged fragmentary sectional view taken along the line 2l-21 in FIG. 17.
FIG. 22 is a fragmentary side elevational view of a po tion of the cutting mechanism as seen from the line 22-22 in FIG 17.
FIG. 23 is an enlarged transverse sectional view taken along the line .3 23 in FIG. 2B and illustrating the strip clamping mechanism of the machine in successive positions.
fragmentary top plan view of the clamping mechanism shown in FIG 23., together with a portion of the Strip pull mechanism.
FPS. is a longitudinal sectional view taken gcner ally along the line LES--25 in FlG. 2H and showing the strip pull mechanism Flt 2s is a transverse sectional view taken along the line .2-- 25 in FIG 25.
FIG 27 is an enlarged fragmentary sectional view taken along the line 27-17 in FIG. .23.
FlG. 28 is a sectional view taken along the line 28- 8 in FIG. 27.
FIG. 2 is rt fragmentary sectional view similar to a portion f FIG. 27 but showing certain parts of the ma chine in a different posit on.
FIG 30 is a fragmentary plan view of the pull mecha nism as seen from he line 30-30 in FIG. ZFJ.
FIG. 3! a it tginentary longitudinal sectional view of One of tht: acuurn lielts and associated parts for the machine.
F G 32 is a fragmentary longitudinal plan view as seen from the li e 52-32 in FIG. 31.
FIG. 33 is an enlt-irged fragmentary side view ofa segment of the vacuum belt shown in FIG. 31.
FIG. 34 is an enlarged transverse sectional view taken along the line 34-34 in FIG. 3|. 5 FIG. 35 is an enlarged transverse sectional view taken along the line 35--35 in FIG. 28. with certain parts omitted for purposes of clarity.
FIG. 36 is a fragmentary sectional view taken along the line 36 -36 in FIG 28.
FIG. 37 is a fragmentary sectional view taken along the line 37--37 in FIG. 2B but with certain components in a different position.
FIG. 58 is an enlarged transverse sectional view taken along the line 3S-38 in FIG. 28.
FIG. 3*) is a fragmentary transverse sectional view taken along the line 39-39 in FIG. 2B.
FlG. -t-l is a fragmentary top plan view similar to a portion of FIG. 2C and showing one of the completed aprons as it continues its movement through the machine.
FIG. 41 is a longitudinal sectional view taken generally along the line 41 41 in FIG. 40.
FIG. 42 is a fragmentary transverse sectional view taken along the line ll -42 in FIG. 40.
FIG. 43 is a schematic representation of the pneumatic system of the machine.
FIGS. 44A and 44B collectively comprise a schematic representation of the electrical system of the machine.
DESCRIPIION OF A PREFERRED EMBODIMENT Referring to the drawings, there is shown a machine for manufacturing hilt aprons such as the aprons illustrated in FIG. 7. Each of the aprons 50 includes a main body portion formed from a rectangular sheet 51 and a single cord or strip 52. In the illustrated embodiment the sheet 5] and the strip 52 advantageously are of nonwoven Fibrous materiaL although in other arrangements various woven fabrics or nonporous materials such as polyethylene, rubber, etc, may be employed. The strip 52 forms both a neck loop 53 and tie elements 314 and S5 for the apron and is of a length sufficient to enable the tie elements to be secured either behind or n from of the wearer. The longitudinal edges of the sheet. 5! are folded over the main body portion oithe sheet and are adhesively held in place to provide side Items 56 and 57. Following the manufacture of the apron. the machine folds it longitudinally and transversely in the manner illustrated in FIGS. 8-10 for stacking and packaging.
In order to facilitate the detailed description of the machine illustrated in the drawings, there will first be given a discussion of the general mode of operation of the machine 'l'hat is. before describing the construction and arrangement of various parts of the machine, a descri tion will. he given of its overall function in producing the successive sheets 51 and applying the strips 52 IIIClVili to form the aprons 50.
G Ii N ERA L OPERATION The shee s 51 are fabricated from a continuous nonwoven welt 60 which is stored in roll form on an unwind stand (at or ther suit ilile source. The web 60 is drawn g from ll'lt. strand till over a receiving table 62 by a pair of drive rollers 63 and 64. The table 62 forms a part of the machine frame 65. and this frame defines a longitudina ly cxtetiding feed path for the web material along which the various manufacturing operations are performed.
As the web 60 moves onto the table 62, it passes over an idler roller 67, then around a dancer arm roller 68 and then over a second idler roller 69. The rollers 67 and 69 are suitably supported by the table 62. while the roller 68 is carried at the free end of a dancer arm 70. The opposite end of the arm 70 is pivotally mounted on the unwind stand 61 such that the arm is free to swing in an upward direction from the position illustrated in FIG. 1A. The arm 70 and the associated rollers 67, 68 and 69 operate as a storage device to store a predetermined length of the web 60 along the feed path. The stored length preferably is at least equal to the length of each apron to be produced.
The table 62 serves as a side hemming station for the web 60. As the web moves upwardly from the dancer arm roller 68 and over the roller 69, it passes beneath a pair of spaced adhesive units 72 and 73 (FIG. 2A). The units 72 and 73 are respectively disposed a short distance above the longitudinal edges of the web 60 and are arranged to apply beads of adhesive thereto as the web continues its movement. The adhesive preferably is heated in order to reduce its viscosity and thus increase the flowability of the adhesive onto the web, and in some cases a suitable heat lamp (not shown) is employed to maintain the adhesive at an elevated temperature after its application. The longitudinal edges of the web are then turned in an upward direction as the web moves past two stationary posts 75 and 76, and shortly before the web reaches the downstream end of the table 62 a pair of folding devices 77 and 78 turn over the upstanding edges to form a narrow fold along each edge. Immediately thereafter, the web passes between the drive rollers 63 and 64 to crease the thus formed folds. The folds are adhesively secured to the main body portion of the web to produce the side hems 56 and 57.
Upon emerging from between the drive rollers 63 and 64, the web 60 is led through a second storage device including a roller 80 carried by a dancer arm 81. The dancer arm 81 is pivotally supported by the frame for the table 62 and is movable in an upward direction from the position shown in FIG. 1A in response to movement of the web 60 along the feed path. After passing around the roller 80, the web proceeds over an idler roller 82. With the dancer arm 81 in its lowermost position (the position shown), indicating maximum web storage, the arm actuates a limit switch 83 to stop the drive rollers 63 and 64 in a manner that will become more fully apparent hereinafter.
The web 60 proceeds from the idler roller 82 to a second pair of drive rollers 85 and 86 disposed along the feed path. The rollers 85 and 86 are supported by a table 87 and serve to advance the web through a cutting mechanism 90 including a pair of opposed cutting rollers 91 and 92 on the downstream side of the drive rollers. A knife or blade 93 on the roller 91 makes point contact with the roller 92 and is arranged to cut the web along a straight line which extends in a direction transverse to the webs direction of movement along its feed path, thus forming the successive sheets 51.
As each of the sheets 51 leaves the cutting mechanism 90, it moves toward a first folding station indicated generally at 95. The folding station 95 includes a sheet supporting table 96 and two vacuum belts 97 and 98 (FIG. 2B) which serve to hold the sheet 51 flat while advancing it into position. During the movement of the sheet toward the folding station. it passes beneath spaced groups 100 and 101 of stationary adhesive units. The adhesive units are arranged to form corresponding groups 102 and 103 (FIG. 4) of bond lines on the sheet adjacent the forward opposed corners thereof. These bond lines extend in directions parallel to the direction of movements of the sheet along its feed path and are laid down as the leading edge of the sheet moves beneath the units 100 and 101 and proceeds for a distance of about one foot along the path. In the illustrated embodiment there are five lines in each of the groups 102 and 103 with approximately two inches between adjacent lines. Each of the lines illustratively is ten inches long with the exception of the outside lines which are twelve inches.
The vacuum belts 97 and 98 are mechanically linked to the drive rollers and 86 (FIG. 1A). When the rollers 85 and 86 have advanced a sufficient quantity of web material through the cutting mechanism to the folding station to the drive rollers and the vacuum belts are shut down to bring the sheet to rest at the folding station.
During the time each of the sheets 51 is being indexed into position at the folding station 95, a strip mechanism 105 is effective to draw strip material across the feed path on the downstream side of the cutting mechanism 90 and to position a strip 52 in spaced juxtaposition with the sheet at the folding station. As best shown in FIGS. 11 and 12, the material for the strip is unwound from a supply reel 106. The material moves from the reel 106 through a folding device 107 and then past an adhesive dispensing unit 108 in a direction opposite to the direction of the sheet 51 and in parallel relationship therewith. The device 107 produces an open median fold of V-shaped cross-section in the strip, and the unit 108 thereupon inserts adhesive into the fold. The strip proceeds around a group of idler rollers 109 in a storage assembly 110 to crease the fold and provide sufficient time to set the adhesive.
The thus folded strip 52 proceeds through a pair of drive rollers 111 and 112 and then alternately around spaced idler rollers 113 and corresponding dancer arm rollers 114. The rollers 114 are carried on a pivotally supported dancer arm 11S and cooperate with the rollers 113 to store a substantial length of the strip mate rial. The length of the stored material should be at least equal to that of the strip for each of the aprons 50.
From the dancer arm 115 and the last idler roller 113 the path of the strip material extends around an upstanding capstan 116. The capstan 116 engages a single side of the strip and is independently driven to apply driving force to the strip as it changes direction and approaches the feed path of the sheet 51. At a particular point in the operation cycle, the free end of the strip is firmly gripped by a clamping mechanism 17 when in the position illustrated by full lines in FIGS. 23 and 24. The mechanism 117 cooperates with a piston 119 within a cable cylinder 120 which extends transversely over the sheet feed path a short distance downstream of the point at which the sheet 51 emerges from the cutting mechanism 90. In response to the movement of the piston 119 from the position shown in FIG. 23, the mechanism 90 is carried across the machine to the position illustrated in dash lines. In this latter position the strip 52 is disposed in a predetermined location above the incoming sheet 51 as illustrated in FIG. 5.
As the sheet 51 indexes into position at the folding station 95 (FIG. 2B), a neck pull mechanism 122 draws the neck loop portion 53 of the strip 52 in a downstream direction to produce a V" configuration. The mechanism 122 includes a depending roller 123 (FIGS. 6 and 25) which is longitudinally reciproeable along the center line of the sheet feed path between two stationary posts 125 and 126. The movement of the roller 123 is controlled by a cable cylinder 128. This cylinder is centrally located a short distance above the feed path and extends over the folding station 95 from a position adjacent the strip mechanism 105. Upon the downstream movement of the roller 123 in response to actuation of the cylinder 128, the roller engages the center of the strip and draws it between the posts 125 and 126. The strip comes to rest with the two legs of the \l" in respective juxtaposition with the spaced groups 102 and 103 of adhesive lines on the sheet 51.
With the strip 52 in position above the sheet 51 at the folding station 95, two triangular folding plates I30 and 131 (FIG. 2B) are actuated to fold the opposed corners of the sheet over the legs of the strip and into contact with the adhesive groups 102 and 103. The plates 130 and 131 are hinged to the table 96 and move in unison from a position substantially coplanar therewith (the position shown in FIG. 36) to a position in which the plates overlie the sheet as illustrated in FIG. 37. The plates 130 and 131 are controlled by respective pneumatic cylinders 132 and 133. Upon the operation of these cylinders, their corresponding piston rods 134 and 135 move in an upward direction to swing the plates over the table 96 and adhesively secure the legs of the V-shaped strip and the opposed corners of the sheet 51 to the main body portion of the sheet.
During the time the folding plates 130 and 131 are pressed against the sheet 51 at the folding station 95, the free end of the strip 52 is released by the clamping mechanism 117. The cable cylinder 120 returns the mechanism 117 across the feed path to its initial position, that is, the position shown in full lines in FIGS. 23 and 24, and the mechanism is actuated to sever the strip 52 from its supply and to firmly clamp the free end of the strip material in preparation for the succeeding sheet. The neck pull mechanism 122 also is returned to move the roller 123 back to the position shown in full lines in FIG. 25 preparatory to the receipt of the succeeding strip. As the roller 123 leaves its downstream position (the dotted line position), a depending finger 137 engages the neck loop 53 on the strip 52 to carry the neck loop back over the sheet 51 from the position shown in FIG. 7 to that shown in FIG. 8 and to deposit it on the leading portion of the sheet. The pneumatic cylinders 132 and 133 (FIGS. 36 and 37) thereupon return the folding plates 130 and 131 to release the sheet.
In response to the return of the folding plates 130 and 131, the vacuum belts 97 and 98 (FIG. 2B) again begin to advance the sheet 51, which is now in the form of the completed apron 50, along the feed path. The apron 50 proceeds onto two additional vacuum belts 140 and 141 which carry the apron to a second folding station 142, and the movement of the belts is then arrested to maintain the apron in position at the second station. During the aprons advance. a succeeding sheet 51 moves into position at the first folding station 95.
The folding station 142 includes a pair of plates 145 and 146 which are arranged to produce two lengthwise folds and thus reduce the width of the apron in the manner illustrated in FIG. 8. Each of these folds illustratively is of the order of five inches from the corresponding edge of the apron. As best shown in FIG. 38, the plates and 146 operate under the control of pneumatic cylinders 148 and 149 having piston rods 150 and 151, respectively. The cylinders 148 and 149 are actuated simultaneously to pivot the plates 145 and 146 in an upward and inward direction about longitudinally extending hinges 152 and 153 to produce the folds. Upon the completion of the folds, the plates 145 and 146 are returned to their initial positions.
Thereafter, the vacuum belts 140 and 141 continue the advance of the apron 50 onto an additional vacuum belt 155 at a third folding station 156. A single folding plate 158 is disposed at this latter station and is con nectcd to the supporting structure by a median longitudinal hinge 160. In response to the actuation ofa pneumatic cylinder 162 (FIG. 39), a piston rod 163 within the cylinder moves the plate 158 about the hinge into overlapping relationship with the apron 50. A longitudinal median fold is thus produced in the manner illustrated in FIG. 9.
Following the longitudinal folding of the apron 50, the folding plate 158 is returned to its initial position, and the vacuum belt 155 resumes the advance of the apron along its feed path to a guillotine folding station 165 (FIG. 1B). As best shown in FIG. 41, a vertically reciprocable folding plate 167 is located at the station 165 above the nip between two pinch rollers I69 and 170. As the apron 50 moves over the rollers 169 and 170, it is engaged by the plate 167 to tuck the apron between the rollers, thus producing a transverse median fold in the manner illustrated in FIG. 10. The completed and folded apron proceeds in a downward direction, as viewed in FIGS. 18 and 41, and is directed by an angularly disposed guide plate 172 onto an outfeed conveyor 175.
A more fully detailed description of particular components of the machine will now be set forth.
THE CUTTING MECHANISM The cutting mechanism 90 is best shown in FIGS. 16-21. The mechanism includes a bottom plate which rests on the machine frame 65 and extends in a transverse direction with respect to the feed path of the web. Two bearing blocks 182 and 183 are located on the plate 90 at opposite sides of the frame, and these blocks extend in an upward direction and support a top plate 184. The rollers 91 and 92 are journalled in the blocks 182 and 183 between the plates 180 and 184 with the peripheral surfaces of the rollers in spaced relationship with each other.
The rollers 91 and 92 are skewed in opposite directions relative to one another. Thus, in the illustrated embodiment the upper or knife roller 91 forms a clockwise angle of about 1, as viewed in FIG. 16, with respect to the transverse dimension of the web, and the lower or anvil roller 92 forms a counterclockwise angle of about I, as viewed in this figure, with respect to the webs transverse dimension. The cutting blade 93 is located in a diagonal groove 185 in the roller 91 and is oriented at an angle, illustratively about 2, with respect to the axis of the roller.
The knife roller 91 includes a series of spaced bores 187 along its length. As best shown in FIG. 21, each of the bores 187 communicates with the groove 185 and accommodates a set screw 188 in engagement with the